Era and I have been fortunate to learn a ton from the HIV experts here – many of which came up in report today. Here’s a few of my faves.
The nadir is critical for assessing degree of immune compromise
- The nadir is the lowest CD4 count which has been recorded in the patient’s HIV course – usually when they are off ART or haven’t started it yet.
- If a patients stops taking ART, their CD4 count rapidly drops to their last nadir.
- When you evaluate a patient in whom you suspect medium or long term non-adherence, you should suspect their CD4 is at their nadir.
PCP is hard to diagnose definitively, common (in AIDS patients), and deadly. Know the illness script then use your pretest probability + rapid, imperfect tests to decide on empiric treatment.
- my personal core illness script goes something like… human with CD4<250, subacute dyspnea and dry cough, exertional hypoxemia. There are MANY variations.
- Two things that are not suggestive of PCP
- pleural effusions (basically never)
- cavitary lung lesions (almost never)
- PCP does pnuemothoraces! that’s why it’s called pneumocystis.
- We have written many prior pearls on the rapid, imperfect diagnostic tests – LDH, beta D glucan, chest CT. Here’s a smattering of those
- First line therapy for severe PCP is TMP-SMX. Nothing else works as well, so if someone has an allergy
- For severe PCP, add steroids
- severe means a PaO2 < 70 on room air OR
- Aa gradient < 45
An extremely elevated ferritin in patients with AIDS has a short differential
- It’s most suggestive of histoplasmosis, cocci and disseminated TB
- Other things on the epic ferritin ddx in general
- stills dz
- acute liver failure
I’ll try to post another set of these next HIV/ID report. Let me know if you have favorites for me to highlight!